Integrating Water Conservation And Planting Patterns In Dryland And WUE Enhanced Mechanism

It is very important in science and practice to integrate water conservation and planting patterns, and enhance water use efficiency (WUE) in Dryland farming areas, north of China. In this dissertation, 4 models of integrated water conservation and planting patterns were studied in field experiments, and their mechanisms of yield improvement and WUE enhancement were discussed by testing soil and crop characters. The results can be provided as theoretic basis and technical support for dryland faming in north China. The main conclusions are as follows:1. Dryland micro-catchment planting model-catchment areas and planting areas are arranged in successively. The catchment areas are shaped of ridge and covered plastic film and the planting areas are shaped of furrow and planted crops. The furrow and ridge planting model can collect rainwater, decrease evaporation and improve crop root-zone soil moisture condition effectively.The results show that the 4 kinds of rainwater collection patterns: Wide Ridge Mulching ( WRM ), Hard Material Mulching ( HMM ), Narrow Ridge Mulching with Plant in Cover ( NRMin ), Narrow Ridge Mulching with Plant out of Cover ( NRMout), on some degree, all can collect rainwater and increase soil moisture. The effects order is as follows: WRM, HMM, NRMin, NRMout. They are as 2.36, 2.07, 1.88 and 1.69 times as controlled one. And increasing yield ratio were 27.4%, 20.9%, 13.3%, and 7.7% respectively, and WUE were increased 0. 46, 0. 38, 0. 16 and 0. 06kg/m3. The WRM model is assessed as best one.2. Perforated plastic film coving: In order to increase the effectiveness of small rainfall and improve the ventilation of covered soil, perforated plastic film and covering technique were developed and produced with a large scale. It is verified that the perforated film can have the rainfall pass through the film and improve the soil moisture of covered soil. The soil water content in covered perforated film can be increased 30% than that of common film covered.The soil CO2 content increased with the areas of film covered. The CO2 content in 5 treatments: covered common film 1.4m in width (CF1.4), common film 0.8m in width (CF0.8), perforated film 1.4m in width (PF1.4), perforated film 0.8m in width (PF0.8) and no covered (NC) were 49, 32, 27.6, 24.2, and 4.6 (CO2 mol. m -2. s-1 ) respectively. The results show that covered perforated film can improve the soil ventilation. Inverse proportion to soil CO2 content, the root vitality in above 5 treatments were 32.2, 43.8, 43.2, 57.6 and 66.4 (TTC g. g-1. h-1 ) respectively.3. Water harvesting and supplemental irrigation (SI) is a most effective way to meet the water requirement of crop production in dryland. Different runoff-inducing surface were setup and runoff and minimum rainfall which produce runoff were determined. Then, we did field experiment and explored the amount and timing of SI in winter wheat and maize. For dryland winter wheat, everytiming of SI can increase yield and increase yield effects order as follows: jointing stage, flowing stage, and before winter. The effect were greater with amount of SI increasing because winter wheat is growing in season of rarely rainfall. For dryland maize, it is growing in season of rainy and worm simultaneously and the effect of SI is determined by amount and timing of rainfall. Supplemental irrigation in time is more important than amount of SI.4. Wide-bunch with close grow planting ( WBCGP) configuration : For meet the water-saving and Low-Head Irrigation system in agriculture production, a new kind of subsurface emitter-porous emitter was created. It is made from a kind of rigid micro-particles and technical process in manufacturing include: adhesion, molding and solidification and so on. Based on the water conductivity difference in various soils, variant types of porous emitter were made with different size particles and densities.Water transport through the root-zone soil is calculated using the HYDRUS-2D model. In general we obtained a good agreement between the measured and modeled results for water con...